JFrame 图像在帧调整大小时显示

发布于 2024-11-18 11:56:09 字数 188 浏览 4 评论 0原文

我有这个 JFrame 包含 JPanel 的子级，其中它显示以这种方式声明的图像。

BufferedImage image = ImageIO.read(filename);

程序正确显示图像。但唯一的问题是，它需要调整框架大小才能显示图像。

有没有办法在框架出现后显示图像？

原文

I have this JFrame containing a children of JPanel wherein it displays the image which is declared in this manner.

BufferedImage image = ImageIO.read(filename);

The program displays the image properly. But the only thing is, it requires to resize the frame to display the image.

Is there a possible way to display the image once the frame appears?

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迷路的信 2024-11-25 11:56:09

您应该覆盖 paintComponent(Graphics g) 并在其中绘制图像。在这种情况下，您应该对 JPanel 组件执行此操作（我认为？如果没有，请对您所引用的 JComponent 执行此操作）。另外，由于 Swing 不是线程安全的，因此请确保这些修改是在 EDT 中执行的。

示例

public class Demo{
    private static BufferedImage bi;
    
    public static void main(String[] args){
        try{
            loadImage();
            
            SwingUtilities.invokeLater(new Runnable(){
                @Override
                public void run(){
                    createAndShowGUI();
                }
            });
        }
        catch (IOException e){
            // handle exception
        }
    }
    
    private static void loadImage() throws IOException{
        bi = ImageIO.read(new File("src/resource/braveheart.PNG"));
    }
    
    private static void createAndShowGUI(){
        final JFrame frame = new JFrame();
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        
        final JPanel panel = new JPanel(){
            @Override
            protected void paintComponent(Graphics g){
                Graphics g2 = g.create();
                g2.drawImage(bi, 0, 0, getWidth(), getHeight(), null);
                g2.dispose();
            }
            
            @Override
            public Dimension getPreferredSize(){
                return new Dimension(bi.getWidth(), bi.getHeight());
            }
        };
        
        frame.add(panel);
        frame.pack();
        frame.setLocationRelativeTo(null);
        frame.setVisible(true);
    }
}

输出

在此处输入图像描述

记住这一点很重要该示例忽略渲染提示，因此当您最大化 JFrame 时，图像质量会很差。 :)

编辑

在回答这个问题时，我假设您对 Swing 有基本的了解。我想我假设太多了。值得一提的是，所有组件都应该在实现（即变得可见）之前添加到顶级容器中。这将确保渲染所有内容而无需调整框架大小。正如其他人所建议的，您可以简单地使用 JLabel 来渲染图像，然后将其添加到您的 JPanel 中。相反，我提倡定制绘画，这是完全可以接受的，而且对我来说，更干净。

You should override paintComponent(Graphics g) and draw the image therein. In this case, you should do this for the JPanel component (I think? If not, do this for the JComponent(s) you're referring to). Also, since Swing is not thread-safe, ensure these modifications are performed in the EDT.

EXAMPLE

public class Demo{
    private static BufferedImage bi;
    
    public static void main(String[] args){
        try{
            loadImage();
            
            SwingUtilities.invokeLater(new Runnable(){
                @Override
                public void run(){
                    createAndShowGUI();
                }
            });
        }
        catch (IOException e){
            // handle exception
        }
    }
    
    private static void loadImage() throws IOException{
        bi = ImageIO.read(new File("src/resource/braveheart.PNG"));
    }
    
    private static void createAndShowGUI(){
        final JFrame frame = new JFrame();
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        
        final JPanel panel = new JPanel(){
            @Override
            protected void paintComponent(Graphics g){
                Graphics g2 = g.create();
                g2.drawImage(bi, 0, 0, getWidth(), getHeight(), null);
                g2.dispose();
            }
            
            @Override
            public Dimension getPreferredSize(){
                return new Dimension(bi.getWidth(), bi.getHeight());
            }
        };
        
        frame.add(panel);
        frame.pack();
        frame.setLocationRelativeTo(null);
        frame.setVisible(true);
    }
}

OUTPUT

enter image description here

It's important to keep in mind that this example ignores rendering hints, so when you maximize the JFrame, the image quality will be very poor. :)

EDIT

When answering this question, I assumed you had a basic understanding of Swing. I suppose I assumed too much. It is important to mention that all components should be added to the top-level container before it's been realized (i.e. made visible). This will ensure that everything is rendered without having to resize your frame. As others have suggested, you could have simply used a JLabel to render the image, and then added it to your JPanel. Instead, I promoted custom painting, which is perfectly acceptable, and to me, cleaner.

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